4 papers
Gamma-positivity for a Refinement of Median Genocchi Numbers
Sen-Peng Eu, Tung-Shan Fu, Hsin-Hao Lai +1
We study the generating function of descent numbers for the permutations with descent pairs of prescribed parities, the distribution of which turns out to be a refinement of median…
The Minimum Number of Dependent Arcs and a Related Parameter of Generalized Mycielski Graphs
Hsin-Hao Lai, Ko-Wei Lih
Let D be an acyclic orientation of the graph G. An arc of D is dependent if its reversal creates a directed cycle. Let m(G) denote the minimum number of dependent arcs over all acy…
When is the Direct Product of Generalized Mycielskians a Cover Graph?
Hsin-Hao Lai, Ko-Wei Lih, Chen-Ying Lin +1
A graph is said to be a cover graph if it is the underlying graph of the Hasse diagram of a finite partially ordered set. The direct product G X H of graphs G and H is the graph ha…
Chordal Graphs are Fully Orientable
Hsin-Hao Lai, Ko-Wei Lih
Suppose that D is an acyclic orientation of a graph G. An arc of D is called dependent if its reversal creates a directed cycle. Let m and M denote the minimum and the maximum of t…